Filter



Feb. 9,l 1937. sfF. BRIGGS 2,070,039 I FILTER Filed Dec. ll, 1935 2 Sheets-Sheet 1 4 Feb. 9, 1937.

S. F. BRIGGS FILTER 2 Sheets-sheet 2 Filed Dec. ll, 1935 Patented. Feb. 9, 1937 UNITED STATES PATENT oFFlcE -aoionas FILTER Stephen' F. Briggs, Chenequa, Wis., assignor to Briggs & Stratton Corporation, Milwaukee,

Wis., a corporation of Delaware Application December 11, 1933,l serial No. 701,801

bricating system of automobile engines in which` a force pump is supplied with oil from 4the crank case sump and the discharge or output of the pump leads to the bearings and also to the inlet of the lter unit. The iilter unit is thus connected in parallel with the bearings and also in parallel with a pressure relief valve with which systems oi this type are equipped. The relief valve functionsin the event the lter unit becomes completely clogged or passage of oil therethrough is impossible for some other reason,

Inaccordance with this invention, the admission of oil to theiilter unit is controlled by a spring pressed valve which, of course, opens at'a lower pressure than the pressure relief valve. When the pressure built up by the pump is sufcient to open the spring pressed valve admitting 2 oil to the i'llter unit, the oil pressure on the bearings drops because of the additional return circuit to the. inlet of the pump afforded by the viilter unit. When the iilter is new, this pressure ldrop may be enough to deprive the bearings -of needed oil unless the opening to the lter is restricted. Y

. In the past, a xed oriice of small'capacity provided the inlet to the lter to insure the bearings receiving the proper supply of oil when the iiltering element was new or became punctured. However, as the ltering element clogs up, its resistance to the flow of oil therethrough increases so that. the pressure before, or ahead, of the ltering'element,l which may be termed back pressure, likewiserises. This increases the pressureon the bearings and consequently the supply of oil to the bearings lwith the result that the ow of oil through the lter is lessened and the usefulness of the lter rapidly decreases.

With the above objection to the existing-practice in mind, it is another tion to provide novel means for connecting the filter unit with the lubricating system in such a manner that the supply oi oil to the lter is metered according to the magnitude of the resistance or back pressure of the lter so as to keep the pressure on the bearings substantially constant and thereby not minimize the amount of oilpassing' through the iilter unit. More specically, it is an object of this inven-- Vthe lubricating system, upon the tion to provide a valve mechanism for connecting a. filter unit with a pressure lubricating system, adapted to open and establish an initially small communication between the filter unit and pressure exceeding a predetermined degree, and having means to automatically increase the degree oi?,` communication in response to a rising resistance of back pressure created ahead of thefllter unit as dirt accumulates therein.A

With theA above and other l0 objects in view which will appear as the description proceeds, my invention resides in the novel construction, combination and arrangement of` parts substantially object of this inven-v ing to the bestmodes I lvalve d connected designated generally the ilter unit, the oil is v casethrough a duct I0.

as hereinafter described and'more particularly 15 defined by the appended claims, it beingv understood that such changes in the precise embodi-v ment of the hereindisclosed invention may be made as come within the scope of the claims.

In the accompanying drawings, I have illus- -trated two complete examples of the physical K embodiment of my invention constructed accordhave so far devised forthe practicala-Dplication of the principles thereof, and in which:

Figure 1 is a View partly in side elevation and partly broken away and in section showing. a iilter unit equipped with the improved valve l mechanism of this invention; y

Figure 2 is a view similar 'to Figure 1 illustrating a modied embodiment of the invention; and Figure 3 is a diagrammatic view illustrating the manner of connecting the illter unit of ,this` invention with the pressure lubricating system of an internal combustion engine. 35

Referring now more particularly to the accompanying drawings in which like numerals indicate like parts throughout the several views, and particularly to Figure 3, the numeral 5 desig.. nates a conventional internal combustion engine 40 equipped with a pressure lubricating system illustrateddiagrammatically as comprising a force pump 6 arranged to take oil from the crank case of the engine and force it out through a circulatory system 1. The main pressure feed line yof 45 the circulatory system 1 has a pressure relief therein and connects with branch ducts leading tothe various bearings 8. It also connects with the inlet of a iilter unit by the numeral 9 through 50 the novel valve mechanism forming the subject matter of this invention. After passing through returned to the crank The iilter unit s may be of any desired` design 55 v in Figure l, comprises an outer shell I I having intersects the bore I 8 and communicates at one anintegral bottom I2 and a removable cover I3.

Disposed within the shell I2, is a removable lter core or -cartridge I4, shown in the present instance as comprising a mass of brous material contained withinan inner shell I5. To preclude the oil trickling down along the inner wall of the Shen l5, the fibrous material 1s preferably cemented to the inner surface oi' the shell I5.

'Ihe open top of the shell Il is closed by a foraminous screen I9, to retain the brous material in place and lprovide access to the iilter material.

Attached to the bottom wall of the outer shell is the valve mechanism for connecting the filter unit in the lubricating system. It comprises a body I1 having two-spaced vertical bores I8 and I9 opening to its top and communicated with inlet and outlet ports 20 and 2| respectively, by which the unit is connected in the system. The communication between the inlet port 20 and the bore I3 is normally interrupted by a yieldably held valve 22 to normally close o communication between the inlet port 20 and theinterior oi the outer shell with which the bore I8 communicates. 'I'he outlet port2lis at all times in communication with the bore I9.

At its upper inner end the b'ore I9 is counterbored to receive a cork gasket 23. Engaging the 'cork gasket is a anged outlet opening 24 leading from the interior of the filter cartridge so that the interior of the filter cartridge 'is at all times in direct communication with the outlet port 2|.

The valve 22 is slidable in.a bore 25 which end with a smaller bore 26'communicating with the inlet port 20, and its other end with a larger bore 21 which intersects the bore I9 and has its outer open end internally threaded.

'I'he shoulder afforded by the juncture of the bores 25 and 26 provides a valve seat with which the forward end of the valve 22 isyieldably engaged by a compression spring 28. The spring 28 has one end seated in a drilled recess in the valve and its'other end engages an adjustable .'stop 29 threaded in the outer open end of the bore 21.

The extreme outer end of the threaded bore 21 is preferably closed by a plug 30.

That end of the valve member 22 which is disposed within the bore 21, carries a flange 3|, which has a snug t -in the bore 21 to act as a piston and is'so-located with respect to the juncture between the boresy 25 and 21 that when the valve is closed, as shown, a space is left betweenthe flange and the inner end of the bore 21. Leading to this space and communicating it with the interior of the outer'shell II, is a port 32.

'I'he-spring stop 29 is adjusted so that the spring 23 holds the valve 22 closed until a predetermined pressure has been built up within the lubricating system, which, howevenis less than that at which the pressure relief valve I opens, whereupon the valve 22 is opened against the action of the spring,4

permitting the flow oi' lubricant into the filter unit and through the same, to be discharged back into the crank case.

After the system has been at rest for a short period, whatever pressure there may have been on the outlet side of the lter will have been relieved by drainage of the oil into the crank case sump through the outlet 2 I. 'I'hepressure in the chamber around the outside of the filter mass also will have been relieved through seepage through the lter. The pressure in the bore I3 is accordingly zero.

in the inlet 20, which pressure builds up to the predetermined value necessary to yopen the valve 22.

Immediately upon opening of the valve'22, theo pressure in the inlet 29 is partially relieved so that the valve has a tendency to return to its seat or to flutter. It the lter interposes little resistance to the oil flow therethrough so that pressure is built up in the outlet bore .|9, the eiect of the pressure at the outlet on the opposite end of the valve will aggravate the tendency of the valve to4 utter.

Ordinarily, however, and particularly after the filter has been in use for some p'eriod of time and contains a considerable amount of dirt, there is not much outlet pressure and the ilow of oil through the, outlet may bea mere trickle.

'Ihe tendency of the valve to utter is overcome in the present invention by the provision of the port 3.2 and the piston ilange 3| operating in the cylinder 21. Through the/ port 32 the pressure at the inlet side of the illter is imposed on the piston 3| so thatthe drop in pressure on the end of the valve 22 resulting from its opening is compensated i'or.

When the filter cartridge is fresh,- the amount of back pressure created thereby is slight, but after ithas been in 4use a while and dirt and foreign matter accumulates therein, the back pressure increases. 'I'his back pressure ordinarily would have the same eil'ect upon the valve 22 as increasing the strength of the spring 23 so that the valve would not open at the predetermined `pressure. Hence, in the conventional lter, the

period of usefulness of the cartridge is short.

The present invention entirely nuilies this objectionable eifect oi' back pressure on the valve and accomplishes this purpose by the communication of the interior of the outer shell with the space between the piston ange 3| and the inner end of the bore 21 through the port 32. Inasmuch as the outer face offthe flange 3| is 'not subjected to the back pressure, by applying the fluid pressure of the interior of the outer r shell on the flange 3|, the effect of the back pressure on the valve is entirely nulliiied so that the only force holding the valve closed is that of the spring 23 plus the slight pressure at the outlet of the filter. The pressure on thepiston ange' 3| obviously increases as the filter becomes clogged and the resistance to the ow of oil therethrough increases. Consequently, regardless of the amount of back pressure built up the predetermined 28 is set.

It isalso to be observed that upon the opening of the valve 22 the pressure on the bearings drops by virtue of the fact'that -an additional return to the inlet -of the pump is provided. To

pressure to which the spring t preclude too great a drop in oil pressure at the admits suiiicient oil for eiiicientV 'within the outer shell,the valve 22 will open at the communication afforded by the port 32, the

back pressure ahead of the iilter unit is imposed upon the flange 3| so that as the back pressure and the resistance to the iiow of oil through the lter unit' rises, the valve 22 is opened further. In other words, the flow of oil to the lter unit is metered according to the resistance of the lter unit to the flow of oil therethrough. By opening the valve 22 further, the resistance to the flow of oil into the filter unit is lowered thus keeping up the flow of oil through the fliter Vand maintaining the lter action with as little hindrance as possible until the filter is com- Y pletely clogged. Hence, the effective life of the filter is materially increased. l

The valve mechanism of this invention may be modified, if desired, as shown in Figure 2. In this embodiment of the invention, the iilter cartridge 35 is mounted on a central perforated tube 36, the lower end of which connects to the return duct l0. The. valve mechanism is mounted on the upper endpf the central tube 36 and comprises a tubular body 31 attached to the upper end of the tube and extending upwardly to project through the cover38 ofthe outer shell. A partition 39 divides the'tubular body into upper and lower chambers 40 and 4l respectively.

Threaded into the outer end of the upper chamber 40 is a nipple 42, which also serves to hold the body portion 31 assembledvwith the cover 38. The nipple 42 is internally threaded for the attachment of the intake tube leading from the system 1. The lower end of the nipple l2 provides a valve seat with which a valve 43 engages. The valve 43 is mounted on a stem 44, which is slidably received in a bore 45 in the partition wall 39. and within the Vlower chamber 4l, the valve stem has a piston 46 attached to it-.to bear against an expansive spring 41 confined between the pistonand a washer 48 resting on the upper end of the central tube 36. The spring 41 corresponds to the spring 28.in the embodiment shown in` Figure 1 and yieldably maintains the valve 43 with the interior of the filter unit through portsA 5.0 so that as the back pressure builds up within the filter unit, its action on the piston 46 has the eiect of weakening the spring 41.

From the foregoing description taken in connection with the accompanying drawings, it will be readily apparent to those skilled in the art that this invention provides controlled communication between a pressure lubricating system and a filter unit whereby the supply of oil to the lter is metered according to the resistance of the filter to the passage of oil therethrough in such amanner as to keep the pressure' on the bearings substantially constant and the flow of oil through the filter substantially undiminishedfor a long period of time.

Beneath the partition wallV What I claim as my invention is:V

1. Incombination with a pressure lubricating system, a filter unit including an inlet chamber,

a filter-mass and an outlet chamber, means to communicate the inlet chamber of the lter unit with the system including a valve, `yieldable means to hold the valve closed, said vyieldable means being opposed by the pressure of the system and yielding to permit opening of the valve when the pressure witrhin the system exceeds a predetermined value, and means 'f responsive`to back pressure created within the inlet chamber of the filter unit to weaken the' effect of said yieldable means -on th'e valve and open the valveA farther as the back pressure builds up.

2. In combination with a pressure lubricating system, a filter unit including an inlet chamber, a filter mass and an outlet chamber, means to connect theiilter unit with-the system including a valve controlling communication between the inlet chamber and the system and adapted to open whenthe pressure within the system exceeds a predetermined value, a piston connected with the valve, a cylinder in which lthe piston operates communicated-with the inlet chamber of the filter unit whereby the piston vis acted upon by back pressure created within said inlet chamber by the retardation of flow through the filter mass, and a spring to oppose the movement o f the valve` by the pressure of the system and the back pressure.

3. .In a filter device including a housing to receive fluid to be ltered, said housing having an l inlet for unfiltered fluid and an outlet for filtered fluid, a valve to close said inlet and operable by fluid pressure, a. spring to hold said valve closed effect of .back pressure on the valve and insure y the opening of the valve in response to the predetermined uid pressure.

4. In combination with a' pressure lubricating system, a filter unit havingv an inlet and an outlet, means to communicatethe inlet and outlet with the system, means normally closing the inlet and responsive to a predetermined pressure differential at the inlet and outlet to open and connect the inlet of the iilter unit with the system, the opening 0f said means to vconnect the filterY unit with the system altering said pressure differential by an amount varying with the condition of the filter, and pressure equalizing means to compensate for said varying pressure diiferen. tial.

5. In combination with a pressure lubricating system,A a illter unit having an inlet and an outlet, means to connect the inlet and outlet of the iilter unit with the system, a valve normally closing the inlet and responsive to a predetermined pressure differential at the inlet and outlet of the filter unit to open and connect the inlet of the unit with the system, and means connected with said Isystem including a'valve normally closing the inlet, yielda'blemeans to hold the valve closed,

said yieldable means being opposed by the pressure of the system and yielding to enable opening of. the valve whenl the pressure within the system exceeds a' predetermined value, ducts connecting vopposite pressure responsive surfaces of said valve with the inlet and the outlet ot the iilter upon opening of said valve, and means responsive to back pressureA created withiny the duct at the inlet' by the 'illtver unit to weaken the eect of'v the yieldable means on the valve tol insure opening of the valve upon theattainment o! said predetermined pressure within` the system regardless of the degree of back pressure.

pressure at which the valve opens, said valve having a surface acted on by pressure at the outlet of said lter unit, and 'means connected with the valve and acted upon by pressure at the inlet of the filter unit inwardly of said valve to overbalance the pressure at the outlet of the lter.

STEPHEN F. BRIGGS. 

